JPS58192934A - Fuel interrupting device for decelerating internal- combustion engine - Google Patents

Abstract

PURPOSE:To prevent the production of an unburnt HC in an initial stage of deceleration, by forcibly interrupting a suction port of a high pressure plunger pump. CONSTITUTION:A comparator 105 is used to obtain a return angle of an accelerator pedal for judging a deceleration condition where a fuel should be interrupted. A comparator 103 is used to judge whether a stepping angle of accelerator pedal is close to an idling position. When signals from these comparators becomes high levels simultaneously it indicates that a driver operated to fully interrupt a supply of fuel by decelerating a vehicle sharply. In this case, a power transistor 112 is energized and a relay 113 is magnetized, thereby interrupting a suction port of plunger pump. In this manner, there is no chance of small amount of fuel being injected in an initial stage of deceleration with a result in the reduction of HC discharge.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel cutoff device for reducing harmful exhaust components, particularly hydrocarbons (HC), during deceleration of a fuel-injected internal combustion III engine.

A distribution type fuel injection pump used in a diesel engine is generally constructed as shown in FIG.

(8san Jidosha Co., Ltd.: Service Bulletin No. 418 “Datsun Bluebird” published in April 1980, pp. 42-5
(Page 8) Fuel is sucked from an inlet 1 of the pump body by a feed pump 3 driven by a drive shaft 2 connected to an engine output shaft.

The supply pressure of the fuel discharged from the feed pump 3 is controlled by a pressure regulating valve 4, and the fuel is supplied to a pump chamber 5 inside the pump housing.

The fuel in the pump chamber 5 lubricates the working parts and is simultaneously sent to the pressure plunger pump 6 through the suction boat 12.

The plunger 7 of this pump 6 is fixed to an eccentric disk 8 connected to the drive shaft 2, and is connected to the drive shaft 2 via a joint 2A.
It is driven in synchronization with lIfl11 rotations.

The eccentric disc 8 has the same number of face cams 9 as the number of engine cylinders, and while rotating, the face cams 9 move the rollers 11 disposed on the roller ring 10.
Each time the cam crosses over, it reciprocates by a predetermined cam lift.

Therefore, the plunger 7 reciprocates while rotating, and this reciprocating movement pressurizes the fuel sucked from the suction boat 12, and forces the fuel from the distribution boat 13 through the delivery valve 14 to an injection nozzle (not shown).

At this time, the fuel injection timing can be freely adjusted by changing the relative position between the face cam 9 and the roller 11 using the roller ring 10.

The roller ring 10 is driven by a plunger 21 that responds to the fuel pressure in the pump chamber 5.

On the other hand, the amount of fuel to be injected is determined by the position of a spill ring 16 that covers a spill boat 15 formed on the plunger 7.

During the fuel injection stroke in which the plunger 7 moves to the right, when the opening of the spill boat 15 passes the right end of the spill ring 16, the fuel that had been pumped from the inside of the plunger pump chamber 68 to the distribution boat 13 is transferred to the spill boat 15. The fuel then escapes to the pump chamber 5 and ends the fuel injection.

Therefore, if the spill ring 16 is displaced to the right relative to the plunger 7, the fuel injection end time will be delayed and the fuel injection amount will be increased, whereas if the spill ring 16 is displaced to the left, the fuel injection end time will be brought forward. Therefore, the amount of fuel injection decreases.

The position of the spill ring 16 is controlled via a link lever part 19 by an adjusting lever 20 that is linked to an accelerator pedal (not shown) and a governor mechanism 18 that is driven by the rotation of the drive shaft 2. The fuel injection amount is increased or decreased in order to maintain the engine speed corresponding to the engine speed.

The governor mechanism 18 is built into the soil layer of the injection pump body, and the flyweight 18C is connected to the flyweight holder 18b, which is integrally formed with the gear 18a, at the junction point 18D.
It is attached so that it can rotate freely around the center. When the flyweight holder 18b slides and rotates around the governor shaft 18e according to the rotation of the drive shaft (2) transmitted through the gear 18a, the flyweight 18
G also rotates and spreads around the junction 18D due to centrifugal force.

Then, the governor sleeve 18f, which fits into the governor shaft 18e and engages with the flyweight 18C, is moved forward by the flyweight 18C.

On the other hand, the link lever 19 contacts the governor sleeve 18f, is rotatable about the fulcrum A, and is engaged with the spill ring 16 via the pivot pin 18q.

Therefore, when the governor sleeve 18f moves forward, the link lever 19 rotates around the fulcrum A, and the spill ring 16
is moved to the left in the figure, thereby controlling the fuel injection amount in inverse proportion to the increase in rotational speed.

Additionally, in order to stop the engine when the ignition key is turned off, a fuel cutoff valve 30 linked to the ignition key is installed to close the intake boat 12 in a de-energized state.

In FIG. 1, the axis of the plunger 21 is 90° for convenience of explanation.
The feed pump 3 is shown rotated by 90 degrees, and the axis of the feed pump 3 is also rotated by 90 degrees.

In this distribution type fuel injection pump, when the accelerator pedal is released during deceleration, the adjusting lever 20 is interlocked with this, and the upper end of the lever 23 is returned to the right. Therefore, the spill ring 16 moves to the left around the fulcrum A. At this time, by a combination of levers and springs, if the pump rotation speed exceeds a predetermined value with the accelerator pedal released, the spill ring 16 should be pumped to the left in relation to the drive of the spill ring 16 to the left by the governor 18. It can be set so that all the fuel escapes from the spill boat 15, thereby making it possible to cut off fuel injection during deceleration.

However, if the accelerator pedal is suddenly released, the movement of the spill ring 16 may be delayed due to the expansion and contraction of the springs or the friction of the contact parts, and a small amount of fuel may be injected during this movement at the beginning of deceleration. be.

In this case, combustion of the fuel will be incomplete and unburned fuel will be discharged as is.

The amount of HC discharged due to these factors sometimes amounted to about 10% of the total amount of HC discharged in the general test mode.

Therefore, in this invention, when an excessive deceleration state is detected, fuel injection I! By forcibly and instantly shutting off the suction port of the high-pressure plunger pump until the liI adjustment means reaches the position where the fuel injection amount is zero, the generation of unburned HC at the beginning of deceleration is prevented. It is an object of the present invention to provide a fuel cutoff device during deceleration as described above.

The present invention will be explained below based on the drawings.

FIG. 2 shows the first embodiment of this invention.
01 is an accelerator pedal sensor, which outputs a voltage low signal 81 proportional to the accelerator depression angle.

A sample and hold circuit 102 holds the value of the voltage signal S1 when the sampling clock is input until the next sampling clock is input, and outputs it as a voltage signal S2.

103 is a comparator that compares the signal S with the comparison value vr;
A pulse signal S5 is output which becomes a high level when Vrl>81° and a low level when Vrl is less than Sl.

Note that the comparison value Vr, + is preferably a value corresponding to a case where the accelerator depression angle is small (not depressed much).

104 is a differential amplifier that measures the degree of decrease in the accelerator depression angle per unit time, that is, the degree of deceleration, and sieves 82-81 from the above signals and generates a voltage signal S3 corresponding to the difference.
Output.

A comparator 105 has a comparison value Vr for determining a deceleration state in which fuel is cut off, and outputs a pulse signal S4 which becomes high level when 83>vr2 and low level when 83<vr2. Note that the comparison value Vr2 is set to a value that allows an appropriate deceleration state to be detected, taking into consideration the period of the sampling clock described above.

The AND circuit 106 outputs a pulse signal S6 that becomes high level only when signals 84, 85, and 810 (described later) are simultaneously high level.

107 is a monostable multivibrator, which outputs a pulse signal S that maintains a high level for a predetermined period 111T from the moment when the output S6 of the AND circuit 106 rises to a high level.
Outputs 7.

108 is a 1N rotational speed sensor, which outputs a pulse signal S8 having a frequency proportional to the engine rotational speed.

109 is an F-V converter, which outputs a voltage signal S9 proportional to the frequency of the pulse signal S8.

Comparator 110 compares signal S9 with comparison value Vr, and S9
>v", outputs a pulse signal 810 which becomes high level and becomes low level when 89<Vr3r.

This comparison value vr corresponds to the fuel cutoff limit rotation speed during deceleration, and vr may be set on the condition that the engine does not stall.

111 is an AND circuit which outputs a pulse signal 811 which becomes high level only when the signals S5, 87 and S10 become high level at the same time.

Power transistor 112 conducts when signal 811 is at a high level and supplies current to the coil of relay 113. When the relay 113 is energized, the terminals 113b and 1130 are short-circuited, and when the relay 113 is not energized, the terminals 113a and 113C are short-circuited. Terminal 113a is connected to the battery via an ignition switch, terminal 113b is an open terminal, and terminal 113c is connected to fuel cutoff valve 114. Therefore, when the current is cut off during deceleration, the fuel cutoff valve 114 is fully closed to cut off the fuel.

This fuel cutoff valve 114 is constructed as shown in FIG.

A flow path 1 is provided at the center of the valve body 120 that opens and closes the suction port 12.
25 is provided, and the opening and closing of the flow path 125 is performed by an auxiliary valve body 121 housed inside.

Springs 122 and 123 bias valve bodies 121 and 120, respectively, downward in the valve closing direction.

When the coil 124 is energized, the internal auxiliary valve body 121 lifts.

In this case, only the force determined by the cross-sectional area of the flow path 125 and the differential pressure across the valve body 121 is applied to the auxiliary valve body 121, so it is easy to lift.

When the auxiliary valve body 121 lifts, the differential pressure between the suction port 12 and the pump chamber 5 decreases, so the valve closing force applied to the valve body 120 decreases, and the valve body 120 lifts easily.

Therefore, according to this fuel cutoff valve 114, fuel can be cut off during engine deceleration operation, and fuel injection can be resumed in a responsive manner after deceleration.

Next, the action will be explained.

Assuming that the accelerator pedal is suddenly released from steady driving, the return speed of the accelerator pedal is determined by the change in the output of the accelerator pedal sensor 101 during the sampling clock period (81-81), that is, the differential amplifier 104. is represented by the output S3.

If this output S3 is larger than the comparison value ■r, the comparator 10
5, it is determined that a large deceleration is occurring, and the output S4 becomes high level. Also, when the accelerator pedal depression angle is returned to a position (near the idling position) that makes the fuel injection amount almost zero, that is, sensor output S1
is the comparison value Vr.

When the value becomes smaller, the output S5 of the comparator 103 becomes high level.

Therefore, outputs S5 and 83 become high level at the same time because
This is a case where the driver attempts to reduce the fuel injection to zero with a large deceleration. On the other hand, if the engine rotational speed at this time is higher than the predetermined engine rotational speed, that is, the output S10 of the comparator 110 is also at a high level, the output $6 of the AND circuit 106 is at a high level, and the monostable multivibrator 1
The output S7 of 07 is switched to a high level for a predetermined time T after the driver performs the deceleration operation. This time T may be set based on the time it takes for the spill ring 16 shown in FIG. 1 to actually reduce the fuel injection amount to zero after the above operation.

In this way, when the output of the quasi-stable multivibrator 107 is at a high level, when the engine speed is above a predetermined speed and the depression angle of the accelerator pedal is below a predetermined value, the outputs S5 and S10 of the comparators 103 and 110 are When both are at high level, the output 811 of the AND circuit 111 becomes high level.

As a result, power transistor 112 becomes conductive, relay 113 is energized and terminals 113a and 1130 are cut off, and fuel injection is immediately cut off.

On the other hand, fuel injection is restarted when any one of the inputs to the AND circuit 111 is switched to low level, in other words, when at least one of the following conditions is satisfied.

1. Time T has passed.

2. The engine rotation speed has fallen below a predetermined speed.

3. The depression angle of the accelerator pedal exceeds a predetermined value.

At this time, the output 311 of the AND circuit 111 becomes low level, terminals 113a and 113c of the relay 113 are short-circuited, and current from the battery is supplied to the fuel cutoff valve 11-4, thereby opening the cutoff valve 114. fuel injection is restarted.

Next, FIG. 4 shows a second embodiment.

In this embodiment, the fuel cutoff valve 114 is kept closed until the actual position of the spill ring 16 is detected and the fuel is cut off due to the position of the spill ring 16 during deceleration. The same parts as in FIGS. 1 to 3 are designated by the same reference numerals, and only the essential parts are illustrated. A metal non-measuring body 130 is fixed to the spill ring 16, and the displacement sensor 131 outputs a frequency signal 820 corresponding to the distance to the non-measuring body 130. The F-V converter 132 converts the signal 820 into a voltage proportional to the frequency and outputs it as a distance signal (spilling position signal) S21.

Comparator 133 compares output 821 with comparison value Vr,
It outputs a signal 822 which becomes high level when 21>Vr and becomes low level when 821<Vr.

The comparison value vr may be set based on the voltage output by the F-V converter 132 when the spill ring 16 is in a position where the fuel injection amount is approximately zero.

134 is an AND circuit that becomes high level when outputs 85, 810, 822, and 823 (described later) are all high level.

The output 824 of the AND circuit 134 is the power transistor 1
At the same time, it is input to the inverter 135.

Triggerd by the rise of the output 825 of the inverter 135, the monostable multivibrator 136 outputs a short pulse signal S26 having a predetermined time width at a high level.

137 is a flip 70 knob and outputs S6 to set terminal S.
, an output 826 is input to the reset terminal R, and an output 823 is output from the output terminal Q.

Therefore, the output signal S23 of the flip-flop 137 is a pulse signal that becomes high level at the rising edge of the signal S6 and becomes low level at the rising edge of the signal S6.

As can be seen from the above, when the engine rotation speed is above a predetermined speed and below a predetermined accelerator pedal depression angle, the spill ring 16 is located at a position where the fuel injection amount is above a predetermined amount (in other words, the position where the injection amount is zero). (when it is to the right of)
When the driver performs a predetermined deceleration operation, outputs S6 and 823 become high level, and outputs 85 and 823 respectively become high level.
810°522 also becomes high level, and the AND circuit 134
becomes a high level output. Therefore, relay 113 is energized and fuel cutoff valve 114 closes to cut off fuel injection.

Then, fuel injection is restarted when at least one of the following conditions is met.

1. The engine rotation speed has fallen below the specified value.

2. The accelerator pedal depression angle has exceeded the specified value.

3. The spill ring 16 has moved to the position where the fuel injection amount is zero.

At this time, the output 824 of the AND circuit 134 becomes a low level, and the fuel cutoff valve 114 opens to start fuel injection.

At the same time, the output 825 of the inverter 135 rises, and the output S26 of the monostable multivibrator 136 becomes high level, resetting the 7-lip 70-tub 137. Therefore, its output 823 becomes low level.

By the way, in this case, if the spill ring 16 is at the zero injection amount position, even if the fuel cutoff valve 114 is opened, the fuel is still cut off. Therefore, under such conditions, when the suction boat 12 is opened during deceleration, there is no need to consider the responsiveness of the fuel cutoff valve 114 when restarting injection, and reacceleration is performed smoothly.

FIG. 5 shows the embodiment of FIG. 3. This controls fuel cutoff during deceleration without detecting the engine speed.

140 is a neutral switch of the transmission, and when it is not in the neutral position, that is, when some gear is engaged, the contact closes and the signal 830 becomes high level. 141 is a clutch switch,
When the clutch is engaged, the contact closes and its output 83
1 is a high level. Only when these outputs 830 and 831 are simultaneously high level, the output 832 of the AND circuit 142 becomes high level. 143 is an AND circuit, and the output S33 becomes high level only when the above-mentioned output 84.85 and the output 832 of the AND circuit 142 are simultaneously high level. Triggerd by the rising edge of the output S33, the monostable multivibrator 144 outputs a pulse signal 834 that maintains a high level for a predetermined period of time (the same as in the case of the first embodiment (may be short).

And the 145 AND circuit outputs these 85°832
．． Only when S334 is at a high level at the same time, the output S35 becomes a high level, making the power transistor 112 conductive.

Therefore, in this case, the transmission is not in neutral, the clutch is also engaged, and the fuel cutoff valve 114 closes to cut off fuel injection during a predetermined deceleration operation.

Then, fuel injection is restarted when at least one of the following conditions is satisfied.

1. Set the gear to neutral.

2. Release the clutch.

3. Push the accelerator pedal to the specified depression angle or higher.

When the gear is set to neutral or the clutch is disengaged, rotational force due to inertia cannot be obtained, so fuel injection is restarted to prevent engine stall.

As explained above, according to the present invention, the means for adjusting the fuel injection 114- during deceleration already reduces the injection amount to zero while moving to cut off the fuel, so that a small amount of fuel is injected. This makes it possible to significantly reduce the emission of HC, which is a harmful exhaust component, especially at the beginning of deceleration.

Furthermore, in the first embodiment, since the fuel injection cutoff period is determined by a simple timing device, the fuel injection is not cut off for an unnecessarily long time, and the fuel injection can be smoothly restored (this is the third example). The same applies to Examples). Furthermore, since the engine speed is included in the return condition, there is no risk of engine stalling, and this is the same in the second embodiment.

Furthermore, in the second embodiment, the position of the spill ring is detected and the fuel cutoff valve is opened when the fuel injection amount reaches the zero position, so that re-acceleration can be performed with good response.

In the third embodiment, instead of detecting the engine speed, two switches are used to detect the gear position and clutch engagement/disengagement, which has the additional effect of simplifying the configuration. arise.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a typical distribution type fuel injection pump. Fig. 2 is a block diagram of the first embodiment of the present invention, Fig. 3 is a sectional view of the fuel cutoff valve, Fig. 4 is a block diagram of the second embodiment, and Fig. 5 is a block diagram of the third embodiment. It is a block diagram. 16... Spill ring, 101... Accelerator pedal sensor, 104... Differential amplifier, 105... Comparator, 108... Rotation speed sensor 1.113... Relay, 114... Fuel Shutoff valve, 120... Valve body, 121
... Valve body, 131 ... Displacement sensor, 140 ... Neutral switch, 141 ... Clutch switch. Patent applicant Nissan Motor Co., Ltd.

Claims (1)

[Claims] A distribution type fuel injection pump equipped with a means for continuously adjusting the fuel injection amount according to the accelerator opening, which includes a means for detecting the accelerator opening, a means for detecting a change in the accelerator opening, and at least both of these. means for determining a deceleration state based on the output of the means; a valve means for cutting off a suction port of the plunger pump during the deceleration; and means for opening the valve means by determining when to restart fuel injection in accordance with the operating state. A fuel cutoff device during deceleration, characterized by comprising: